Formwork for cylindrical columns

ABSTRACT

It is applicable to a formwork made from a tubular body in plasticised wood, rigid plastic or the like, conveniently stabilised by means of an outer envelope made of a glass fiber mesh rolled up helicoidally, with or without the intercalation of a second tubular body made of expanded polystyrene; the improvements of the invention consist in obtaining an inner tubular body in plastic or wood made of a single plate ( 7 ) which width coincides with the perimeter of the formwork to be obtained, having said plate ( 7 ) a continuous internal side ( 8 ) and with an external side ( 10 ) wherein a plurality of longitudinal cuts ( 9 ) are established, evenly distributed, affecting mainly the thickness of said plate, defining weakened zones ( 11 ) allowing an easy deformation of said plate ( 7 ), which is initially flat, in order to convert it into a cylindrical and tubular element.

OBJECT OF THE INVENTION

[0001] The present invention refers to a new formwork for obtainingcylindrical columns, which has been specially conceived as a disposableor single-use element and which is specially adapted for obtainingcolumns made of reinforced concrete.

[0002] The object of the invention is to achieve optimal results byusing such a formwork with a simple and therefore economical structure,with the highest dimensional and formal precision and with an optimumfinishing of the column to be obtained.

BACKGROUND OF THE INVENTION

[0003] In order to build a column made of, for example, reinforcedconcrete, it is required to have a mould or formwork to provide thedefinitive configuration and dimensions to the column; said formworkmust comply with two different but complementary characteristics: itmust assure a perfect superficial finishing of the column and its costhas to be sufficiently low to make it profitable for the constructor,especially taking into account that this is a disposable formwork.

[0004] In this sense it is worth to mention the Spanish patent havingapplication number 9800419, of which the present applicant is the owner,wherein a disposable formwork for columns is described, being structuredfrom a tubular core or body, based on a plurality of expandedpolystyrene pieces, fixed to each other by means of adhesive along theirjoint edges; said tubular core being innerly coated with a plastic sheetconstituting a watertight barrier, fixed to said core by means of anadhesive layer; externally, the whole formwork is completed with areticulated support made of a glass fibre mesh, rolled up helicoidallyon the tubular core and fixed to the same also by means of adhesive, insuch a way that said mesh provides to the whole set an appropriatemechanical rigidity against the radial forces generated by the concretemass to be placed inside the formwork.

[0005] This solution, specially designed for columns having arectangular or square cross section, has been subsequently improved withthe Certificate of Addition to said patent having the application number9802487, wherein it is foreseen to replace the plastic sheet,constituting a watertight barrier and fixed to the core, by a series ofplates made of plasticised wood on their inner side, or made of rigidplastic, said plates being fixable to each other with the help ofadhesive tapes conveniently mounted on their inner side, incorrespondence with the joining edges of the plates, so as to configurean inner tubular body having a substantially smooth and watertightsurface, on which the polystyrene pieces were then placed, constitutingthe intermediate rigid tubular body and on which, in turn, finally, theexternal fixing layer made of said glass fibre mesh rolled uphelicoidally was established, for providing the appropriate mechanicalresistance to the formwork as a whole.

[0006] The aforementioned formwork is still designed for columns havinga prismatic cross-section and the presence of expanded polystyrene isrequired for providing the formwork with an external cylindrical surfacein order to enable the operation leading to the placement of the glassfibre mesh rolled up helicoidally and to enable its functionality.

[0007] Furthermore, the inner adhesive tapes used as watertight meansbetween the plates forming the inner or operative surface of theformwork, even though they have a reduced thickness, they define smallgradings on the external surface of the column, which sometimes may beundesirable.

DESCRIPTION OF THE INVENTION

[0008] The formwork provided by the present invention is basedessentially on the structural philosophy of the Patent of Invention9800419 and solves in a fully satisfactory manner the problems mentionedabove, making it possible to obtain cylindrical columns with a perfectsuperficial continuity and with a maximal structural simplicity of thesame formwork, with the corresponding repercussion in its cost.

[0009] To achieve this, more particularly, said formwork is structuredfrom an annular body in which the rigid plates from the Certificate ofAddition 9802487 which width was coincident with the width of the sidesof the column, are replaced by laminates of reduced width, being morereduced when the bigger is the degree of proximity to the perfectcylinder to be achieved, said laminates being also obtainable fromplasticised wood or from an appropriate rigid plastic, which in any caseare sealed by means of an inner self-adhesive film, covering the wholesurface of the annular body, continuously, so as to avoid the problem ofthe small superficial grading mentioned above and to assure a perfectsealing of the formwork; the whole set is completed with a glass fibremesh rolled up helicoidally on the annular body, for the obvious purposeof fixing said laminates and due to the absence in this case of thetubular body made of expanded polystyrene pieces.

[0010] This basic solution can be taken as a departing point and itpresents only the problem of the lack of formal stability of theformwork which in fact tends to adopt an oval configuration during itsmanipulation, without reaching the total flat state because the externalreinforcement does not allow it; nevertheless this is not an importantproblem because the pressure that will be later exerted by the concretewill urge the formwork to adopt a perfectly cylindrical configuration;however, it may create a certain number of manipulation problems andthis is why it has been foreseen that optionally the structure describedcan be complemented with a series of belts or bands convenientlydistributed along the formwork, having a rigid constitution in order toavoid its deformation; said belts can be metallic in which case theywill be in the form of recoverable adjustable clamps or they can be alsomade of expanded polystyrene, in which case they will be disposable asthe rest of the formwork.

[0011] It has also been foreseen that, in order to provide the formworkwith a structural rigidity, instead of said belts or bands, anintermediate layer of expanded polystyrene being placed between theannular body made of rigid laminates and the external reinforcement, insuch a way that it extends along the whole formwork and is sufficientlythick so as to provide the appropriate structural rigidity.

[0012] According to another embodiment of the invention and in order toachieve a higher precision in the dimensions and in the form and abetter finishing of the column to be obtained, it has been foreseen thepossibility to use, replacing said rigid laminates, a single plate madealso of plasticised wood or rigid plastic, having a width matching theperimeter or circumference of the column to be obtained, with thespecial particularity that said plate includes, in its external side, aplurality of longitudinal cuts, parallel and evenly distributed, withina distance, for example, equivalent to the width of the classicallaminates, said cuts affecting mainly to the thickness of the plate, inan amount of, for example, 80% of said thickness, in such a way that theplate is easily deformable for converting it into a cylindrical tube,but having a continuous internal surface which, in turn, makes itunnecessary to use the classical self-adhesive inner film.

[0013] Optionally, for economical reasons, non plasticised wood can alsobe used, to which a film is fixed on its inner side, preferably at thesame time as it is slotted.

[0014] Furthermore, said slotted plate, after the adoption of thecylindrical configuration, receives the classical external envelope madeof a glass fibre mesh rolled up helicoidally, with or without theintermediate tubular body made of expanded polystyrene contributing tomake it rigid.

[0015] Preferably, and according to another feature of the invention,said external envelope, instead of being structured as a glass fibremesh, can be made of a self-adhesive tape provided with threads of glassfibre exclusively along the longitudinal direction, which are theeffective ones, once the tape has been rolled up helicoidally on therest of the formwork; this eliminates or spares the transversal threadsof the classical mesh and facilitates the fixation of said envelope.

[0016] As a complement to what has been described above and according toanother feature of the invention, it has been foreseen that a pair ofend rings, having a section in “U” and a diameter corresponding withthat of the same formwork, collaborate with said wooden plate; the endsof the wooden or plastic plate are to be introduced inside the rings,once the cylindrical configuration has been achieved, such as tofacilitate the shaping of said plate and to confer a higher rigidity tothe formwork for its transport, while assuring a perfect circular formof the cross section of the formwork during its placement in thebuilding site.

DESCRIPTION OF THE DRAWINGS

[0017] In order to complete the present description and to contribute toa better understanding of the features of the invention, a set ofdrawings according to a preferred embodiment of the invention isincluded for illustrative and not limitative purposes, where

[0018]FIG. 1 shows a perspective view of a formwork for cylindricalcolumns, madeaccording to the object of the present invention, moreparticularly according to the simplest embodiment, in which the formworkis deformable when not in use.

[0019]FIG. 2 shows, according to a representation similar to FIG. 1, thesame formwork of the preceding figure having here belts or bandsappropriately distributed along the same.

[0020]FIG. 3 shows, according to a representation similar to thepreceding figures, the same formwork being stiffened here by means of acontinuous tubular body made of expanded polystyrene.

[0021]FIG. 4 shows, according to a schematic perspective view, the platemade of wood or rigid plastic used in the second embodiment of thepresent invention, in which the external side of said plate is shown.

[0022]FIG. 5 shows a profile of the plate shown in the preceding figure.

[0023]FIG. 6 shows again a profile of the plate shown in FIGS. 4 and 5,once it has adopted the definitive cylindrical configuration of theformwork.

[0024]FIG. 7 shows a diametrical cross section of one of the closingrings used to be coupled to the ends of the plate shown in FIGS. 4 to 6,after the cylindrical configuration of said plate.

[0025]FIG. 8 shows a partial detail in a perspective view of theself-adhesive tape used as external stiffening means of the formwork.

[0026]FIG. 9 shows, finally, a detail in cross section of the tape shownin the previous figure.

PREFERRED EMBODIMENT OF THE INVENTION

[0027] Concerning the figures and more particularly FIG. 1, the formworkof the present invention is structured, according to the simplestembodiment, with an annular body (1) made of a plurality of rigidlaminates (2) which, as mentioned above, may be made of plasticised woodor of rigid plastic; they may be flat, in which case their width will bethe minimum in order to obtain a good circumferential alignment when allof them are coupled to each other, but they could also present a certaincurvature, according to the column to be obtained. The annular body (1)is conveniently stabilised with the help of a glass fibre mesh (3),rolled-up helicoidally on its external side, and is also perfectlysealed by means of an inner film (4), self-adhesive, coveringcontinuously the whole inner surface of the annular body (1).

[0028] A formwork structured in such a way is perfectly valid forobtaining a cylindrical column having a diameter according to the sameformwork; the formwork is deformable when empty, tending to acquire anoval section, and this is the reason for which it has been foreseen thepossibility to include in this structure, according to FIG. 2, aplurality of belts or bands (5), appropriately distributed along theformwork, and made of any convenient rigid material, like, for example,expanded polystyrene or even metal, in such a way that the rigidity ofsaid belts (5) gives the appropriate formal stability to the formwork asa whole during its handling. Said belts or bands (5) are placed on theouter side of the glass fibre mesh, as it can be noted especially in theenlarged detail in FIG. 2.

[0029] However, these belts or bands (5), according to the embodimentshown in FIG. 3, can be replaced by a tubular body (6), also made ofexpanded polystyrene, which can be fragmented in several portions, as itcan also be seen in FIG. 3, to facilitate its coupling to the annularbody (1) made of laminates (2); in any case, the enveloping glass fibremesh (3) remains on the outer side of said tubular body (6) made ofexpanded polystyrene as it can be seen particularly in the enlargeddetail in FIG. 3.

[0030] In such a way, a structurally simple and consequently economicslab is obtained, offering an operative surface tending to form acontinuous cylinder, perfectly sealed against the aqueous componentincluded in the concrete to be received in its interior.

[0031] In the embodiment shown in FIGS. 4 to 7 it has been foreseen toreplace said rigid laminates (2) by a single plate (7) as the basicelement of the formwork, which can be made of rigid plastic or of woodplasticised on the side that will be the internal side (8); said platehas a rectangular configuration, having a length according to the heightof the column to be obtained, and a width according to the perimeter ofsaid column.

[0032] Said plate (7) is initially flat and it is provided, tofacilitate its shaping, with a plurality of longitudinal cuts or slots(9) affecting mainly to its thickness, as it can be seen particularly inFIG. 5; said slots are open towards their outer side (10) and theydefine weakened zones (11) providing the plate (7) as a whole with theappropriate deformability in order to achieve an easy transformation ofthe flat element in FIG. 5 into the tubular and cylindrical element ofFIG. 6.

[0033] The position of said tubular and cylindrical element in FIG. 6 isstabilised with the help of a pair of narrow rings (12), like the oneshown in FIG. 7; said rings have a cross-section in “U” which groove(13) will receive the correspondent end of the tubular body making theplate (7); the lateral branches of the “U” are asymmetric, as it canalso be seen in FIG. 7, in order to facilitate the mounting and theshaping of the plate (7). In this way, the plate adopts, by means of theend rings (12), a perfectly cylindrical configuration. However, saidrings can be made simply with a rectangular section, enveloping theplate (7) and having a weakened zone in order to facilitate theircut-away and their elimination together with the rest of the formwork.

[0034] The plate (7) may present a thickness of about 2.5 millimetersand their slots (9) will have such a depth that the weakened zones (11)will present a height between about 0.3 and 0.5 millimeters; saidgrooves (9) are evenly distributed and separated by a distance between35 and 50 millimeters, depending on the bending radius of the column tobe obtained, the above mentioned data being given as an example becausesaid parameters may vary outside the pre-established limits depending ofthe specific needs in each case.

[0035] Furthermore, the formwork will be stabilised, like in the caseshown in FIGS. 1 to 3, with the help of an envelope on the outer side ofthe plate (7), not shown, made of a glass fibre mesh, rolled uphelicoidally with or without the interposition of a tubular body made ofexpanded polystyrene; similarly, on the outer side of said glass fibremesh a plurality of bands could be established, evenly distributed alongthe formwork, made of any rigid material, in order to collaborate withthe end rings (12) mentioned above.

[0036] The glass fibre mesh (3) shown in the embodiments in FIGS. 1 to3, as well as the one foreseen but not shown in the embodiments in FIGS.4 to 6 can be replaced by a self-adhesive tape (14) made of, forexample, a support (15) of paper or the like, in one of which sides (16)a layer of adhesive glue is included, where longitudinal threads (17)are embedded, evenly distributed, in such a way that the support (15)serves simultaneously as a support for the glass fibre threads (17),physically independent to each other, and, together with its layer ofself-adhesive glue (16), as fixing means of the tape (14) to theformwork, in the absence of the classic transversal threads which whererequired, in the conventional mesh, to keep the position of itslongitudinal threads; this is done without reducing the functionalperformance of said envelope because the only threads that support theefforts to which the formwork will be submitted are said longitudinalthreads (17), which will be substantially transversal to the axis of theformwork after the rolling up of the tape, while the classicaltransversal threads of the band, after said rolling up, where placed inparallel to the axis of the formwork being therefore discontinuous andinoperative.

1. Formwork for cylindrical columns, of the type including an annularbody made of rigid plates, in plasticised wood, rigid plastic or thelike, conveniently fixed in such a way that said annular body adopts, inuse, the section corresponding to the column to be obtained,characterized in that said rigid plates constituting the annular body(1) are made of laminates (2) having a reduced width, more reduced whengreater is the degree of proximity of the formwork to the perfectcylinder, said laminates (2) being fixed to each other to configure saidannular body with the help of an external envelope (3) made of a glassfibre mesh rolled up helicoidally on said annular body, while saidannular body (1) receives innerly a self-adhesive film (4) coveringcontinuously the whole inner surface of all the laminates (2) in orderto provide the formwork with an appropriate tightness. 2 Formwork forcylindrical columns according to claim 1, characterized in thatoptionally, in order to provide the formwork with a complete formalstability when handling the same in an empty state, a plurality of beltsor bands (5) are established on the envelope (3) made of glass fibremesh, conveniently distributed along the formwork and made of a rigidmaterial such as, for instance, metal or expanded polystyrene. 3.Formwork for cylindrical columns according to claim 1, characterized inthat optionally, in order to provide the formwork with a complete formalstability when handling the same in an empty state, a tubular body (6)made of expanded polystyrene, acting as a stiffening element, isestablished between the annular body (1) made of rigid laminates (2) andthe envelope (3) made of glass mesh.
 4. Formwork for cylindrical columnsaccording to claim 1, characterized in that said annular body made ofplasticised wood, rigid plastic or the like, is formed by a plate (7),initially flat, having a length according to the height of the column tobe obtained and a width according with the diameter of said column, saidplate (7) being affected by a plurality of longitudinal cuts or slots(9) open towards their outer side (10) and defining in said plate (7)some lines (11) remarkably weakened, allowing the deformation of saidplate in order to change its original flat configuration into acylindrical, tubular configuration, according to the column to beobtained.
 5. Formwork for cylindrical columns according to claim 4,characterized in said plate is helped by two end rigid rings (12),having a “U” section, defining each one of them an annular groove (13)which receives in its interior the corresponding end of the plate (7),by means of which the perfect cylindrical shaping of said plate (7), andconsequently of the formwork as a whole, is assured.
 6. Formwork forcylindrical columns according to claim 5, characterized in that thelateral branches of the rings (12) having a “U” profile are asymmetric,in order to facilitate the positioning inside the groove (13) of thecorresponding end of plate (7) and hence the cylindrical shaping of saidplate.
 7. Formwork for cylindrical columns according to any of thepreceding claims, characterized in that it is included, as an outerstiffening envelope (3), a self-adhesive tape having a plurality ofglass fibre threads (17), disposed longitudinally and evenlydistributed, in such a way that said band is fixed to the rest of thestructure of the formwork due to its self-adhesive condition, with anhelicoidal path and preferably with a partial overlap of the same, insuch a form that the fibres are in a substantially transversal positionwith respect to the imaginary axis of the formwork.
 8. Formwork forcolumns according to any preceding claim, characterized in that saidself-adhesive tape (14) consists in a support (15) made of a sheet ofpaper or the like, including in one of its sides a layer (16) ofself-adhesive glue wherein the glass fibre threads (17) are embedded.